v3.25.4
Loans and Allowance for Credit Losses - Summary of Inclusive Capitalized Loans (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Student Loan Portfolio By Program [Line Items]      
Total loans $ 2,551,705 $ 2,362,796  
Loans held for sale, at lower of amortized cost or fair value 15,144 128,226  
Total loans, gross 2,436,916 2,265,428  
Bank Holding Company Accounting [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 2,566,849 2,491,022 $ 2,215,886
Total loans, gross $ 2,566,849 $ 2,491,022  
Percentage of total loans 100.00% [1] 100.00%  
Bank Holding Company Accounting [Member] | Loans Held for Investment [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 2,551,705 $ 2,362,796  
Percentage of total gross loans 99.00% [1] 95.00%  
Bank Holding Company Accounting [Member] | Loans Held for Sale at Lower of Amortized Cost or Fair Value [Member]      
Student Loan Portfolio By Program [Line Items]      
Loans held for sale, at lower of amortized cost or fair value $ 15,144 $ 128,226  
Percentage of total gross loans 0.00% [1] 5.00%  
Recreation [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 1,617,221 $ 1,543,243  
Recreation [Member] | Bank Holding Company Accounting [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 1,617,221 1,543,243 [2] 1,336,226 [2]
Recreation [Member] | Bank Holding Company Accounting [Member] | Loans Held for Investment [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 1,617,221 $ 1,422,403  
Percentage of total gross loans 63.00% [1] 57.00%  
Recreation [Member] | Bank Holding Company Accounting [Member] | Loans Held for Sale at Lower of Amortized Cost or Fair Value [Member]      
Student Loan Portfolio By Program [Line Items]      
Loans held for sale, at lower of amortized cost or fair value $ 0 $ 120,840  
Percentage of total gross loans 0.00% [1] 5.00%  
Home Improvement [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 810,237 $ 827,211  
Home Improvement [Member] | Bank Holding Company Accounting [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 810,237 827,211 760,617
Home Improvement [Member] | Bank Holding Company Accounting [Member] | Loans Held for Investment [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 810,237 $ 827,211  
Percentage of total gross loans 32.00% [1] 33.00%  
Commercial [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 123,068 $ 111,273  
Commercial [Member] | Bank Holding Company Accounting [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 123,068 111,273 114,827
Commercial [Member] | Bank Holding Company Accounting [Member] | Loans Held for Investment [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 123,068 $ 111,273  
Percentage of total gross loans 5.00% [1] 4.00%  
Taxi Medallion [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans $ 1,179 $ 1,909  
Taxi Medallion [Member] | Bank Holding Company Accounting [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 1,179 1,909 3,663
Taxi Medallion [Member] | Bank Holding Company Accounting [Member] | Loans Held for Investment [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 1,179 1,909  
Strategic Partnership [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 15,144 7,386  
Strategic Partnership [Member] | Bank Holding Company Accounting [Member]      
Student Loan Portfolio By Program [Line Items]      
Total loans 15,144 7,386 $ 553
Strategic Partnership [Member] | Bank Holding Company Accounting [Member] | Loans Held for Sale at Lower of Amortized Cost or Fair Value [Member]      
Student Loan Portfolio By Program [Line Items]      
Loans held for sale, at lower of amortized cost or fair value $ 15,144 $ 7,386  
[1] Percentage may not foot due to rounding.
[2] Includes loans held for sale and loans held for investment.